Fabrics used as functional decorative coverings, such as bedding, upholstery and window treatments, are typically woven fabrics comprising yarns of cotton, polyester, or cotton polyester blends. The materials are chosen based on the need for such fabrics to be attractive in appearance and texture, durable, stain resistant, and printable. Many factors can influence the ultimate properties of the fabric; these can include the material from which the yarns are formed, the weight of the yarns, the configuration of the yarns (e.g., multifilament, spun, cabled, etc.), and the weave density.
Of these factors, thread count can be particularly important. For example, a "percale" fabric (regarded in the industry as a highly desirable fabric for sheets and other bedding) typically has a thread count of at least 180 yarns per square inch. At such a thread count, fabrics tend to be quite soft, strong and relatively opaque, thereby providing a highly desirable fabric.
Unfortunately, the additional yarns employed to provide a fabric with high thread counts typically drive up the cost of the fabric proportionately. The higher cost is dependent on both the cost of the additional yarns and the need for more loom motions for each inch of fabric produced. As such, many manufacturers produce fabrics with lower thread counts (such as about 120 yarns per square inch) that are less expensive than percale fabrics but have a less luxurious feel.
Because consumers are willing to pay less for these lower cost fabrics, the expense of the additional yarns can be problematic for the manufacturer. Much of the cost of the yarn lies in the production process used to form the yarns rather than in the raw material itself. Most of the yarns employed in these fabrics are spun yarns formed of cotton, polyester, or cotton polyester blends. The processing of spun yarns typically includes carding, drawing, spinning, warping and slashing steps that are performed prior to the yarn being ready for weaving; for ring spun yarns, additional roving and winding steps are also required. The inclusion of these numerous processing steps increases the production cost of the yarns significantly. However, simply omitting yarns from these fabrics (which, of course, already have lower thread counts than the percale fabrics discussed above) in the interest of saving money often results in an unacceptable product. Reducing thread count while keeping yarn sizes constant can result in loose, open constructions that allow light to pass through, battings to show through, or even fibers to percolate out. This can be important for pillows, bedsheets and comforters.